The characteristic features and principal causes of incomplete root fusion and penetration are described. General guidelines on 'best practice' are given so welders can minimise the risk of introducing imperfections during fabrication. As the presence of imperfections in a welded joint may not render the component defective in the sense of being unsuitable for the intended application, the preferred term is imperfection rather than defect. For this reason, production quality for a component is defined in terms of a quality level in which the limits for the imperfections are clearly defined, for example Level B, C or D in accordance with the requirements of BS EN ISO The application code will specify the quality levels which must be achieved for the various joints.
A general review of the causes and acceptance of shape imperfections - Part 2
A review of the causes and acceptance of shape imperfections - TWI
I have heard some people say that with all welding, you must have deep or maximum penetration into the base plate in order for a weld to be strong. If you have shallow penetration, the weld is weaker. The deepest possible weld penetration is always best. Are these statements accurate? To keep the article fairly short, the discussion will be limited to arc welding, two common types of weld joints T and butt and two common types of welds fillet and groove.
Weld defects/imperfections - incomplete root fusion and penetration
Click here for Part 1. This second article on shape imperfections refers mostly to fillet welds but there are two additional butt weld imperfections that require some comment. Penetration becomes excessive when the joint gap is too large, the root faces are too small, the heat input to the joint is too high or a combination of these causes.
Welding is a core activity in the fabrication factory, undertaken by skilled, qualified operatives working to a welding quality management system under the control of a Responsible Welding Coordinator. It is used to prepare joints for connection in the shop and on site, and for the attachment of other fixtures and fittings. Different welding techniques are used for different activities within the fabrication factory.